Currently, more and more old people or babies or enabled peoples or patients cannot move by themselves. They must be carried by wheelchairs. Sometimes, people use cart (or wagons) to transfer pets or goods, while theses works need to apply manpower to wheelchairs, carts, or wagons. Since great manpower needs to drive the wheelchairs, carts, or wagons, the moving ranges of these vehicles are confined to be nearby of the driving people. A frequent event is to transfer the old people or babies to a park for sunny. The servant will feel ill at ease due to a great power being applied, but the wheelchair only be moved within finite ranges.
Therefore, if it is desired to improve the aforementioned defects in the prior art, an easy way is to combine the cart to a bicycle which is frequently used in daily life with a very lower cost. If it wants to do so, it is needed to improve the structure of the cart so that the cart can be combined with a bicycle. Therefore, the structure of the cart is needed to be modified so that it is able to be combined to a bicycle easily and fast for carrying goods or people.